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Thanks for your reply kaare_t. There are about 15 PLCs in different UK locations and each one has 4 or 5 alarms. A number of people have kindly offered advice and most of them have suggested that I install ethernet adapters and set up a SCADA system. Does this sound like a good idea or would you suggest an alternative approach?

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Yes, a SCADA will certainly solve your case. However, SCADA systems can be pretty expensive and you don't have a lot of data you need to collect (and for that matter you don't really need all the functionality that a SCADA system delivers), so I was just thinking if there were any other possible solutions. Regarding a SCADA system, head over to HMI/SCADA section of the forum, maybe someone knows of a "small" SCADA system that can handle your data. 15*5 tags are not much, so you are looking for a small, but functional system. Make sure it's scalable since you might want to expand in the future (suddenly you have 15*10 tags that you want to monitor ). Check out: http://forums.mrplc.com/index.php?/forum/37-hmi-amp-scada/

You will need Ethernet cards/boards for the PLC's to be able to collect data, there are some other alternatives but they will be more complex and more expensive so I'm not going into those at the moment.

Your biggest "challenge" though is to actually access the local networks (LAN) where your PLC's are located. My recommendation is to set up VPN tunnels from your head office to all your locations. Do you have any way of "contacting" your remote sites, or are they completely "stand-alone" today?

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Thanks kaare_t, I will head over to the SCADA section and post a query. At the moment the sites are all 'stand alone' - we don't monitor them at all. When an alarm goes off the operator on duty deals with it. I'd appreciate any advice you can offer re the setting up of the VPN tunnels - I had naively assumed that the ethernet module would be able to send the data to our office computer.

Both of your PLC's that you have mentioned will communicate Modbus. (Serial or Ethernet)
I would suggest to look at the following free software package: AdvancedHMI.
It was written in VB.Net and runs on Visual Studio. AdvancedHMI will take care of the communication to the PLCs. Communication to any database is straight forward with some simple program statements.https://sourceforge.net/projects/advancedhmi/

Regards,
Garry

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There are units that you can bolt on to the programming port of an FX PLC that will set up a VPN automatically. A similar unit at the control end (your offices) would be able to poll the rest of the units in the field and grab any alarm information that you need.

Can you advise on the best module to add to each PLC to allow them to communicate with the PC?

Is there a program I can install on my computer that will work with the data from the PLCs in a user-friendly way?

It’s a big ask I am sure but I am looking for a program that will log all the PLCs’ alarms in a database and automatically send SMS/emails to the appropriate staff when alarms go off.

The PLCs have been running for years but we’re new to the idea of communicating with them and saving data etc. Any advice about hardware/software/how you would do it etc would be gratefully received.

I have one of each of the same PLC's that you are using, and have them connected to my PC through the network for programming and monitoring, but only with the MELSEC GX software, at this point. I am using existing NetCOM 111, they are 1 port RS232 to Ethernet modules, and drivers on my PC that make it a virtual serial port. It works well for programming and monitoring the PLC program in real time, but outside the software, can't currently communicate to obtain data via ModBUS RTU.

For ModBUS, I can't justify installing an additional serial module, additional NetCOM, IP address, and virtual serial port for each PLC. I need to use the program port connection I've already established, and have read that it has been done, but, havn't received necessary details or possible software tools. So far in my investigation, I believe that the programming port only works on the MC programming protocol, and I'd need some software to convert, or need to learn how to make a driver to convert that from and to ModBUS format for SCADA software.